The present invention relates to a method of detecting a defect of semiconductor circuit elements, in particular of field effect semiconductor circuit elements, a circuit configuration, and an electronic controller with such a circuit configuration.
Electronic control devices for motor vehicle brake systems perform functions at an increasing rate that either contribute to driving safety or lately even comprise basic vehicle functions such as the braking function itself. Examples of functions for improving driving safety are anti-lock control (ABS) or driving dynamics control (ESP: Electronic Stability Program). The braking function as such is carried out by the electronic control unit of the brake in more recent electronic brake systems, such as the ElectroHydraulic Brake (EHB) or the ElectroMechanical Brake (EMB). Therefore, ever increasing demands are placed on the reliability, failure tolerance and error handling of the electronic control units.
It is known in prior art to install safety devices in electronic control units for motor vehicle brake systems, which permit detecting any occurring defects of the electronic components contained in the control units. Upon detection of such a defect, appropriate countermeasures such as the deactivation of the control unit or switch-over of the control unit into an emergency mode may be taken. Safety-relevant circuit parts may have a double or multiple (redundant) design to identify defects. Errors arising can be detected in many cases by comparing the functioning of the multiply provided circuit parts.
Semiconductor circuit elements such as power field effect transistors (power MOSFET's, FET's) are employed among others for actuating the electromechanical hydraulic valves provided to control the brake pressure.